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[OPENMP] Fix for PR28581: OpenMP linear clause - wrong results. 

If worksharing construct has at least one linear item, an implicit
synchronization point must be emitted to avoid possible conflict with
the loading/storing values to the original variables. Added implicit
barrier if the linear item is found before actual start of the
worksharing construct.

llvm-svn: 311013
This commit is contained in:
Alexey Bataev 2017-08-16 15:58:46 +00:00
parent cd21378ff6
commit 8c3edfef6b
3 changed files with 12 additions and 6 deletions
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13
clang/lib/CodeGen/CGStmtOpenMP.cpp
View File

@ -1231,12 +1231,14 @@ void CodeGenFunction::EmitOMPInnerLoop(
EmitBlock(LoopExit.getBlock());
}
void CodeGenFunction::EmitOMPLinearClauseInit(const OMPLoopDirective &D) {
bool CodeGenFunction::EmitOMPLinearClauseInit(const OMPLoopDirective &D) {
if (!HaveInsertPoint())
return;
return false;
// Emit inits for the linear variables.
bool HasLinears = false;
for (const auto *C : D.getClausesOfKind<OMPLinearClause>()) {
for (auto *Init : C->inits()) {
HasLinears = true;
auto *VD = cast<VarDecl>(cast<DeclRefExpr>(Init)->getDecl());
if (auto *Ref = dyn_cast<DeclRefExpr>(VD->getInit()->IgnoreImpCasts())) {
AutoVarEmission Emission = EmitAutoVarAlloca(*VD);
@ -1261,6 +1263,7 @@ void CodeGenFunction::EmitOMPLinearClauseInit(const OMPLoopDirective &D) {
EmitIgnoredExpr(CS);
}
}
return HasLinears;
}
void CodeGenFunction::EmitOMPLinearClauseFinal(
@ -1550,7 +1553,7 @@ void CodeGenFunction::EmitOMPSimdDirective(const OMPSimdDirective &S) {
CGF.EmitOMPSimdInit(S);
emitAlignedClause(CGF, S);
CGF.EmitOMPLinearClauseInit(S);
(void)CGF.EmitOMPLinearClauseInit(S);
{
OMPPrivateScope LoopScope(CGF);
CGF.EmitOMPPrivateLoopCounters(S, LoopScope);
@ -2170,7 +2173,7 @@ bool CodeGenFunction::EmitOMPWorksharingLoop(
llvm::DenseSet<const Expr *> EmittedFinals;
emitAlignedClause(*this, S);
EmitOMPLinearClauseInit(S);
bool HasLinears = EmitOMPLinearClauseInit(S);
// Emit helper vars inits.
std::pair<LValue, LValue> Bounds = CodeGenLoopBounds(*this, S);
@ -2184,7 +2187,7 @@ bool CodeGenFunction::EmitOMPWorksharingLoop(
// Emit 'then' code.
{
OMPPrivateScope LoopScope(*this);
if (EmitOMPFirstprivateClause(S, LoopScope)) {
if (EmitOMPFirstprivateClause(S, LoopScope) || HasLinears) {
// Emit implicit barrier to synchronize threads and avoid data races on
// initialization of firstprivate variables and post-update of
// lastprivate variables.

4
clang/lib/CodeGen/CodeGenFunction.h
View File

@ -2761,7 +2761,9 @@ public:
/// and initializes them with the values according to OpenMP standard.
///
/// \param D Directive (possibly) with the 'linear' clause.
void EmitOMPLinearClauseInit(const OMPLoopDirective &D);
/// \return true if at least one linear variable is found that should be
/// initialized with the value of the original variable, false otherwise.
bool EmitOMPLinearClauseInit(const OMPLoopDirective &D);
typedef const llvm::function_ref<void(CodeGenFunction & /*CGF*/,
llvm::Value * /*OutlinedFn*/,

1
clang/test/OpenMP/for_linear_codegen.cpp
View File

@ -422,6 +422,7 @@ int main() {
// CHECK: [[A_PRIV:%.+]] = alloca i{{[0-9]+}},
// CHECK: [[B_PRIV:%.+]] = alloca i{{[0-9]+}},
// CHECK: [[C_PRIV:%.+]] = alloca i{{[0-9]+}},
// CHECK: call void @__kmpc_barrier(
// CHECK: store i{{[0-9]+}}* [[A_PRIV]], i{{[0-9]+}}** [[REFA:%.+]],
// CHECK: store i{{[0-9]+}}* [[C_PRIV]], i{{[0-9]+}}** [[REFC:%.+]],
// CHECK: call void @__kmpc_for_static_init_4(